1. Field of the Invention
The present invention relates to propulsive wings and traction kites, used for applying a traction force and/or pulling a load. More particularly the present invention relates to traction kite having a generally tubular inflatable leading edge comprised of multiple segments, with certain segments comprised of deformable material such that the leading edge is easily deformed to improve the overall turning performance and handling of the kite, while still providing sufficient leading edge structural stability.
2. Description of Related Art
The use of kites as a means of propulsion has existed for over a century. Kites were first used as a means of propulsion in pulling boats. Through already popular water and land based board sports such as surfing and snowboarding, the sports of kiteboarding and snow kiting have grown. These sports adapt the principals of surfing and snowboarding to include kites as a method for generating speed. A number of advances, particularly to the design of the kite propulsion system, have led to improvements in safety, increases in top attainable speeds, and improvements in overall performance.
Most traction kites currently used in board sports are constructed with flexible canopy having an inflatable leading edge armature which distributes the load via ropes at the lateral ends and/or are fixed to the leading edge. As used therein the terms “traction kite” or “kite” shall mean a propulsive wing that harnesses wind power to pull a rider through the water or snow on a riding platform (e.g. a board). A traction kite of this type is described in U.S. Pat. No. 4,708,078 to Legaignoux et al., wherein a basic design for a leading edge inflatable (“LEI”) kite is disclosed. Legaignoux discloses an inflatable leading edge having an inflatable armature covered by a flexible envelope. The Legaignoux leading edge is generally formed of material having monolithic deformation characteristics.
As kite sports have evolved, demand for kites with improved performance characteristics has grown. Specifically, kite users desire kites with improved handling and control, faster turning speeds, and more responsive control achieved with minimal user input force. A traction kite is conventionally controlled by a series of control lines, commonly referred to as a bridle. Turning speed and force needed to initiate turning has been found to be an important performance character in tube kites, particularly kites bigger than 9.0 square meters in size. Turning a propulsive kite is typically achieved by deforming one side of the kite with respect to the other side. By elastically deforming one side of the kite, the angle of attack is adjusted, causing the kite to change direction and/or to add power or decrease power (i.e. depower). The ability to twist and deform the kite depends on the elastic (e.g. stretch) characteristics of the material forming the leading edge, the diameter of the leading edge, and inflation pressure. At the same time the leading edge needs to provide structural stability to prevent the tube kite from deformation caused by appearing loads.
In general there has been an increased demand for traction kites having improved performance characteristics for use in kite sports, such as kiteboarding and snowkiting (i.e. snow kiteboarding). The amount that a kite elastically deforms based on a given applied force, which force is created by the user and transmitted through the lines and subsequent bridle structure, is dependent on the ease by which the leading edge of the kite bends and twists. Bending and twisting of the leading edge is directly related to both the design parameters and the characteristics of the materials used in creating the leading edge support structure. Specifically, leading edges with low air inflation pressures that are made from a material with a high elasticity provide the maximum amount of bending, whereas leading edges with high air inflation pressures that are made of material with a low elasticity minimize bending. In any event, however, the leading edge must be rigid enough to provide sufficient support to maintain the stability of the kite when in use.
The prior art, however, fails to disclose or suggest a propulsive wing that maximizes control responsiveness by providing an inflatable leading edge that is capable increased elastic deformation while maintaining sufficient structural rigidity to maintain stability in flight. There is therefore a need for a propulsive wing with an inflatable support structure that is designed to maximize the ease by which the support structure can be elastically deformed, while providing a support structure that is sufficiently rigid to maintain stability during flight.